Most recreational vehicles, such as all-terrain vehicles (ATVs), snowmobiles, and personal watercraft, are powered by an internal combustion engine. The operation of the engine generally is controlled by adjusting the quantity of air and fuel the combustion chambers of the engine receive, and by controlling the timing of the ignition of the air/fuel mixture in the combustion chamber. In the case of fuel injected engines, the timing of the injection of the fuel can also be controlled.
Recreational vehicles typically have one or more throttle valves in the engine's air intake system which are mechanically connected to a driver operated throttle operator, generally by a control cable. The throttle operator, generally in the form of a lever or a twist grip on a handlebar of the vehicle, is used by the driver to open and close the throttle valves to adjust the quantity of air going to the combustion chambers of the engine. An electronic control unit (ECU) located in the vehicle then controls the engine's ignition system, and in the case of fuel injected engine, the engine's fuel injection system, accordingly. In order to have the engine generate more power, the driver would use the throttle operator to cause the throttle valve to open further. Similarly, in order to have the engine generate less power, the driver would use the throttle operator to cause the throttle valve to close. For example, in the case of an ATV moving on a level surface, opening the throttle valve results in the ATV accelerating and closing the throttle valve results in the ATV decelerating.
In some instances, it is desirable to limit the power generated by the engine, to limit the maximum speed of the engine or to have a cruise control function on the vehicle for example. Since in the above-described vehicles the degree of opening of the throttle valve is controlled by the driver of the vehicle, this leaves the ECU to control the ignition and, where available the injection, in order to limit the power of the engine. For example, when the engine reaches a predetermined maximum speed, the ECU will control the engine such that some of the spark plugs are not fired and/or that fuel is not injected in every combustion chamber. This control strategy results however in a rough engine operation which is undesirable.
Recent developments in the field of automotive electronics now allow these vehicles to be equipped with what is known as a throttle-by-wire system. In such vehicles, a throttle operator position sensor senses the position of the throttle operator, transmits this position to the ECU, and the ECU sends a signal to a throttle valve actuator, an electric actuator for example, to adjust the degree of opening of the throttle valve based on the position of the throttle operator. This way, the degree of opening of the throttle valve is also a variable, in addition to the ignition and fuel injection, that can be adjusted by the ECU. Vehicles using such systems can therefore use the degree of opening of the throttle valve to limit the speed of the engine. When a predetermined maximum engine speed is reached or exceeded, the ECU will not cause the throttle valve to be opened further or will cause the degree of opening of the throttle valve to be reduced notwithstanding the fact that the signal from the operator position sensor communicated to the ECU indicates a desire by the driver to increase the speed of the engine.
This greatly improves the control of the engine, however controlling the engine based on the engine speed may not be ideal in some instances. For example, regulations prevent personal watercraft manufacturers from making personal watercraft that can exceed 105 km/h (65 MPH). For the same engine speed, the personal watercraft will go at a different speed depending on the load on the vehicle (i.e. weight of the driver, passengers, and items carried on board). Therefore, the predetermined maximum engine speed must be selected such that the personal watercraft will not exceed 100 km/h no matter how light the load on it is. This causes a reduced performance of the personal watercraft when the load is increased (driver with passengers for example) since it will have a lower maximum speed than when a lighter load is present (only the driver for example). Similar instances also exist for land vehicles.
Therefore, there is a need for a method which ameliorates the control of the engine of the vehicle to control the performance of a vehicle.
Throttle-by-wire systems also simplify the implementation of cruise control systems on vehicles. In automotive applications the cruise control is typically engaged by pressing a button on the steering wheel of the vehicle and can be disengaged by pressing the button again or by pressing the brake. However, this method may not be applicable to every type of vehicle, such as personal watercraft given their lack of brakes.
Therefore there is a need for a novel cruise control engine operation mode.
It is generally preferred that the performance of a vehicle be more restricted when it is operated in the reverse direction than when it is going forward. This can be achieved by using a mechanical transmission that reduces the speed of rotation from the engine to the wheels of the vehicle, for example, along with the direction of rotation when the reverse position of the transmission is selected. However, such transmissions can be complex and add substantial weight to the vehicle, especially for vehicles using a continuously variable transmission (CVT).
Therefore there is a need for a method to ameliorate the control of the performance of a vehicle operated in a reverse direction.